ICSE Class 10 Chemistry
Question 15 of 30
Periodic Table — Periodic Properties & Variation of Properties — Question 22
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Question Question 22
With reference to the alkali metals in Group 1 [IA] and the halogens in 17 [VIIA] explain the trend in ionization potential, electron affinity and electronegativity on moving down the groups in the periodic table.
Below table explains the trends in ionization potential, electron affinity and electronegativity on moving down the groups in the periodic table:
| Alkali Metals Group 1 [IA] | Halogens Group 17 [VIIA] | |
|---|---|---|
| Ionization Potential | On moving down the group both atomic size and nuclear charge increases but atomic size increase dominates over nuclear charge increase hence Ionization Potential decreases down the group. ∴ Li > Na > K > Rb > Cs | Similarly for Halogens too Ionization Potential decreases down the group. ∴ F > Cl > Br > I |
| Electron Affinity | On moving down the group, electron affinity decreases as atomic size increase dominates over nuclear charge increase hence the atom attracts the electrons with a lesser force. ∴ Li > Na > K > Rb > Cs | Here also electron affinity decreases in general on moving down the group but Fluorine is an exception here as it has lesser electron affinity than Chlorine due to its electronic configuration. ∴ F < Cl > Br > I |
| Electronegativity | Similar to electron affinity, electronegativity decreases on moving down the group. ∴ Li > Na > K > Rb > Cs | Electronegativity decreases on moving down the group. ∴ F > Cl > Br > I |